500: Internal Server Error when trying to get oAuth token

I am following smart things documentation smarthings-authorization-doc step by step. It works fine until smarthings login page but after successfully signing in, I see error:

Error 500: Internal Server Error
URI /oauth/authorize
Date Tue Oct 18 22:46:31 UTC 2016

It currently does not direct me authorization page, where I can authorize each device.

This quite likely due at this time to SmartThings cloud performance issues.

I’d keep trying every few hours and see if you “get through”.

Also check to see if the IFTTT SmartApp happens to be installed in one or more of your Locations. It is sometimes best to uninstall it completely from all Locations and starting over.